Improved pulse-free metering pump and methods relating thereto

ABSTRACT

A method of dispensing a continuous fluid flow is described, the method includes: (i) filling a first cylinder chamber, having a first predefined volume, with fluid received through a first manifold from a first fluid inlet; (ii) dispensing the first predefined amount of the fluid present inside the first cylinder chamber through the first manifold to a fluid outlet; (iii) filling a second cylinder chamber, having a second predefined volume, with fluid received through a second manifold from a second fluid inlet, and wherein filling is carried out contemporaneously with dispensing; (iv) exerting, during dispensing, a deflection-causing force on a first housing that is disposed adjacent to the first cylinder chamber; and (v) preventing, using the deflection-prevention feature, transfer of the deflection-causing force from the first housing to a second housing, which is disposed adjacent to the second cylinder chamber and is disposed adjacent to the first housing.

RELATED APPLICATION

This application claims priority from U.S. Provisional Application having Ser. No. 62/204,958, filed on Aug. 13, 2015, which is incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

The present teachings generally relate to pump frame and pump designs. More particularly, the present teachings relate to systems and methods that relate to pump frames and pumps, such as metering pumps, that allow for continuous and pulse-free fluid flow.

BACKGROUND OF THE INVENTIONS

Certain conventional pump designs rely on the action of a piston inside a chamber to draw in and then disperse fluid. When a particular application requires continuous pulse-free fluid flow, these conventional pump designs have not yielded a commercially viable solution.

What are, therefore, needed are systems and methods that provide continuous and pulse-free fluid flow and that are commercially viable.

SUMMARY OF THE INVENTION

To this end, the present arrangements and teachings offers pump frame designs and novel pump designs (e.g., metering pumps) and methods relating thereto that provide substantially continuous fluid flow that is substantially pulse-free.

In one aspect, the present arrangements provide a pump that includes two or more housings inside a pump frame. A deflection-prevention feature inside the pump serves to isolate one or more housings such that a deflection force received at one of the housings is not transferred to the other. The absence of this transfer of deflection force allows an action of a piston inside the pump to draw in and dispense a certain fixed volume of fluid, preferably, at a predetermined pressure. Specifically, at least two of the housings, which house the at least two of the pistons, do not deform during operation of the pump, and as a result, ensures that each of the pistons draw and dispense the same volume of fluid in a reproducible manner. This is particularly useful in metering pumps or in pumps that require continuous, pulse-free fluid flow.

In one embodiment of the present arrangements, the pump includes: (i) a pump frame including: (a) two or more housings disposed inside the pump frame; (b) one or more deflection-prevention features that, during an operative state of the pump, prevents transfer of a deflection force received at one of the housings to another of the housings; and (ii) two or more motors, each disposed inside one of the housings and configured to drive a corresponding piston; (iii) two or more cylinders, each disposed adjacent to a corresponding one of the housings and each of the cylinders having defined therein a cylinder chamber and wherein one end of one of the corresponding pistons is capable of protruding into a corresponding one of the cylinder chambers by a corresponding predefined extent; (iv) two or more manifolds, each includes or is communicatively coupled to a fluid inlet, and wherein each of the manifolds introduces an amount of fluid received from one of the fluid inlets into the corresponding one of the cylinder chambers; and (v) a fluid outlet for dispensing fluid in a substantially pulse-free manner. Preferably, the flow rate from the fluid outlet does not vary more than 0.1% from an average fluid flow rate.

During an operative state of the pump over a period of time, the one or more deflection-prevention features may prevent deformation of one of the housings and/or another of the housings by preventing transfer of the deflection force received at one of the housings to another of the housings. Thus, one or more of the deflection-prevention features allow each of the corresponding pistons to protrude into the corresponding cylinder chamber by a corresponding predefined extent. By way of example, one or more of the deflection-prevention features preferably allows the first piston to continue to protrude into the first cylinder chamber by a first predefined extent and allows the second piston to continue to protrude into the second cylinder chamber by a second predefined extent. In this example, the values of the two predefined extents may be the same or different.

In one embodiment of the present arrangements, one or more of the deflection-prevention features is communicatively coupled to one of the chambers and is not communicatively coupled to another of the chambers. In this configuration, the deflection-prevention feature may at least partially surround one of the housings to prevent coupling of one of the housings with another of the housings or to effectively isolate, at or near a location of the deflection-prevention feature, one of the housings from another of the housings. In certain preferred embodiments, the deflection-prevention feature comprises a structural boundary having defined therein a cavity that is filled with air and/or material.

In another embodiment of the present arrangements, one or more of the deflection-prevention feature, which may be incorporated into the above-mentioned pump, includes two or more compartments, each of which is isolated from the other. In this arrangement, one of the housings is disposed inside one of the compartments and another of the housings is disposed inside another of the compartments. Further, in an assembled configuration of the pump, the deflection-prevention feature at least partially surrounds at least two of the housings to prevent coupling of and/or contact between these two housings.

In certain embodiments of the present arrangements, two or more housings include: (i) a first housing having defined therein a first chamber; and (ii) a second housing having defined therein a second chamber. Preferably, at least one of the housings includes a floating member that is: (i) part of one of the housings; (ii) designed to receive the deflection force from one of the motors and/or pistons; and (iii) isolated from another of the housings.

In one embodiment of the present arrangements, the two or more motors include: (i) a first motor disposed inside the first housing and configured to drive a first piston; and (ii) a second motor disposed inside the second housing and configured to drive a second piston.

In one embodiment of the present arrangements, two or more of the cylinders include a first cylinder disposed adjacent to the first housing and having defined therein a first cylinder chamber and wherein one end of the first piston is capable of protruding into the first cylinder chamber by a first predefined extent. In addition to the first cylinder, two or more of the cylinders also include a second cylinder that is disposed adjacent to the second housing and having defined therein a second cylinder chamber and wherein one end of the second piston is capable of protruding into the second cylinder chamber by a second predefined extent. The first cylinder chamber is designed to store a first predefined volume of the fluid and the second cylinder chamber is designed to store a second predefined volume of the fluid. Preferably, each of the first predefined volume and the second predefined volume is a value that ranges from about 1 ml and about 1000 ml. During operative state of the pump, the deflection-prevention feature may be configured to prevent change in amounts of the first predefined volume of fluid stored inside the first cylinder chamber and/or prevent change in amounts of second predefined volume of fluid inside the second cylinder chamber.

In one implementation of the present arrangements, two or more of the manifolds include: (i) a first manifold that has or is communicatively coupled to a first fluid inlet and that introduces a first amount of fluid received from the first fluid inlet into the first cylinder chamber; and (ii) a second manifold that has or is communicatively coupled to a second fluid inlet, and that introduces a second amount of fluid received from the second fluid inlet into the second cylinder chamber.

In certain embodiments of the present arrangements, the pump further includes two or more screws, each of which is coupled to a corresponding piston and a corresponding motor such that, during an operative state of the pump, each of the corresponding motors drives the corresponding screw and the corresponding piston.

In one implementation of the present arrangements, during operation of the pump, at least two of the pistons operate in a complementary manner (i.e., when one piston is in an active stroke, the other is in standby mode and vice versa), and thereby allowing the pump to continuously dispense the fluid from the fluid outlet. By way of example, dual-piston reciprocating pump or metering pump are capable of operating in complementary fashion.

In another aspect, the present arrangements provide a pump frame that includes: (i) a first housing having defined therein a first chamber; (ii) a second housing including a floating member and having defined therein a second chamber; and (iii) a deflection-prevention feature communicatively coupled to the first chamber, and not communicatively coupled to the second chamber. In this configuration, the second housing is disposed adjacent to the first housing inside the same pump frame. Further, the deflection-prevention feature at least partially surrounds the floating member to prevent coupling, at or near a location of the deflection-prevention feature, of the second housing with the first housing. The deflection-prevention feature may also at least partially surround the floating member to effectively isolate, at or near a location of the deflection-prevention feature, the second housing from the first housing. Preferably, the distance between the first housing and a boundary (closest to the first housing) defining the floating member is a value that exceeds about 0.5 mm.

The floating member of the pump frame may define a partial boundary of the second chamber. During pump operation, the floating member may receive a deflection-causing force. In one embodiment of the present arrangements, the deflection-prevention feature surrounds at least one corner of the second housing that is proximate a corner of the first housing. In this embodiment, the deflection-prevention feature prevents the transfer of the deflection-causing force to the first housing (which has defined therein the first chamber).

In yet another aspect, the present arrangements provide another pump frame. One such exemplar pump frame includes: (i) a first housing having defined therein a first chamber; (ii) a second housing having defined therein a second chamber; and (iii) a deflection-prevention feature that includes two or more compartments, each of which is isolated from the other by an isolating component. In this configuration, the two housings are inside the same pump frame and the first housing is disposed inside or part of one of the compartments and the second housing is disposed inside or part of another of the compartments. In an assembled configuration of the pump, the deflection-prevention feature at least partially surrounds both—the first housing and the second housing—to prevent coupling of these two housings. The above-mentioned isolating component includes a structural boundary having defined therein a cavity that is, in certain preferred embodiments, filled with air and/or material.

The present teaching also provide methods of dispensing a continuous fluid flow. One such exemplar method includes: (i) filling a first cylinder chamber, having a first predefined volume, with the fluid received from a first fluid inlet; (ii) dispensing the first predefined amount of the fluid present inside the first cylinder chamber to a fluid outlet; (iii) filling a second cylinder chamber, having a second predefined volume, with the fluid received from a second fluid inlet, and wherein this filling is carried out contemporaneously with the dispensing described in (i); (iv) exerting, during the dispensing described in (ii), a deflection-causing force on a first housing that is disposed adjacent to the first cylinder chamber; and (v) preventing, using the deflection-prevention feature, transfer of the deflection-causing force from the first housing to a second housing. In this configuration, the second housing is disposed adjacent to the second cylinder chamber and adjacent to the first housing.

In one embodiment, the method further includes pressurizing the fluid inside the first cylinder chamber to a first predefined pressure value. Further, this pressurizing is preferably carried out prior to the dispensing (described in (ii)) from the first cylinder chamber.

In another embodiment, the method further includes: (vi) dispensing the predefined amount of the fluid inside the second cylinder chamber to the fluid outlet; (vii) filling a first cylinder chamber having the predefined volume with the fluid received from the first fluid inlet, and wherein this filling is carried out contemporaneously with the dispensing (of the fluid inside the second cylinder chamber as described in (vi); (viii) exerting, during the dispensing (as described in (vi) from the second cylinder chamber, a deflection-causing force on the second housing; and (ix) preventing, using the deflection-prevention feature, transfer of the deflection-causing force from the second housing to the first housing.

In yet another embodiment, the method further comprises pressurizing the fluid inside the second cylinder to a second predefined pressure value. Preferably, the first predefined pressure value and the second predefined pressure value is a high pressure that ranges from about 500 psi to about 50,000 psi.

In one embodiment of the present teachings, the fluid flow to the fluid outlet has a flow rate that ranges from about 0.00001 ml/min to about 1000 ml/min.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following descriptions of specific embodiments when read in connection with the accompanying figure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side-sectional view of a pump frame, according to one embodiment of the present teachings, which includes a deflection-prevention feature that isolates a housing inside the pump frame.

FIG. 2 shows a side-sectional view of another pump frame, according to another embodiment of the present teachings, which includes another deflection-prevention feature that at least partially isolates more than one housing inside the pump frame.

FIG. 3 shows a side-sectional view of a metering pump, according to one embodiment of the present arrangements, which includes the pump frame of FIG. 1.

FIG. 4 shows a side-sectional view of a metering pump, according to another embodiment of the present arrangements, which includes the pump frame of FIG. 2.

FIG. 5 shows a method, according to one embodiment of the present teachings, for continuously dispensing fluid in a pulse-free manner.

DETAILED DESCRIPTION OF THE DRAWINGS

The present teachings relate to pump frames, pumps, such as metering pumps, and methods related thereto. These systems and methods provide fluid flow that is substantially free of pressure fluctuations or variations. Further, these systems and methods play an integral role in industrial applications where a uniform fluid pressure is critical (e.g., oil and gas rock core flooding or refinery flow simulations). The present arrangements and teachings provide a commercially viable solution effectively provides pulse-free fluid flow that is enclosed, preferably, within a single pump frame.

FIG. 1 shows a pump frame 100, according to one embodiment of the present arrangements and that includes a first housing 102 disposed adjacent to a second housing 106 and both are positioned inside the same pump frame 100. First housing 102 and second housing 106 have defined there a first chamber 104 and second chamber 108, respectively. Second housing 106 further includes a floating member 110 that defines a partial boundary of second chamber 108. Pump frame 100 also includes a deflection-prevention feature 112 to prevent a deflection force received at second housing 106 from being transferred to first housing 102. In other words, deflection-prevention feature 112 effectively isolates, at or near a location of the deflection-prevention feature 112, one of the housings from the other. In one embodiment of the present arrangements, deflection-prevention feature 112 includes a structural boundary having defined therein a cavity that is filled with air or a material.

Deflection-prevention feature 112 may be designed in any configuration that effectively isolates or decouples first housing 102 from second housing 106. During an operative state of the pump, deflection-prevention feature 112 prevents deflection-causing force acting on floating member 110 from being transferring to first housing 102. Similarly, any deflection force received at first housing 102 is not transferred to floating member 110 and/or second housing 106. As will be described in greater detail below, deflection-prevention feature 112 allows a pump (using pump frame 100) to provide continuous fluid flow that is substantially pulse-free.

In one embodiment of the present arrangements, deflection-prevention feature 112 at least partially surrounds floating member 110 of second housing 106. In one preferred embodiment of the present arrangements, deflection-prevention feature 112 surrounds at least one corner of second housing 106 that is proximate to a corner of first housing 102. In this configuration, deflection-prevention feature 112 surrounds at least a portion of two sides (e.g., floating member 110 and an adjacent side) of second housing 106. Thus, deflection-prevention feature 112 may provide deflection prevention on more than a single side of second housing 106.

In another preferred embodiment, deflection-prevention feature 112 surrounds three sides of second housing 106 (e.g., three sides of floating member 110 or, in the alternative, each side adjacent to floating member 110). In this embodiment, deflection-prevention feature 112 isolates three sides of second housing 106 from first housing 102 and, this in affect, allows a substantial portion of second housing 106 to float within pump frame 100. In this configuration, multiple sides of first housing 102, however, may not be isolated within pump frame 100.

The distance between a boundary defining floating member 110 and first housing 102 may be any distance that effectively isolates first housing 102 from second housing 106 and vice versa. In other words, the distance between floating member 110 and first housing 102 prevents any deflection-causing force acting on floating member 110 from being transferred to first housing 102. In one embodiment of the present arrangements, the distance has a value that exceeds about 0.5 mm.

FIG. 2 shows a pump frame 200, according to another embodiment of the present arrangements and that includes a first housing 202 and a second housing 206 disposed adjacent to each other and integrated within the same pump frame 200. First housing 102 includes a first floating member 214 and has defined therein a first chamber 206. Similarly, second housing 206 includes a second floating member 210 and has defined therein a second chamber 208. Pump frame 200 also includes a deflection-prevention feature 202 having a first compartment 216 and a second compartment 218, which are isolated from each other by an isolating component 220. First housing 202 may form a boundary of first compartment 216 and second housing 206 may, similarly, form a boundary of second compartment 286. In this configuration, first compartment 216 at least partially surrounds first floating member 214 and second compartment 218 at least partially surrounds second floating member 210.

In this configuration, deflection-prevention feature 212 surrounds each first housing 202 and second housing 206 on three sides, respectively. In other words, deflection-prevention features 212 isolates three sides of first housing 202 from external portions of pump frame 200. Deflection-prevention feature 212, similarly, isolates three sides of second housing 206 from external portions of pump frame 200 and first housing 202.

During an operative state of the pump, deflection-prevention feature 212 prevents any deflection-causing force acting on first floating member 214 from being transferred to an external portion of pump frame 200 and/or second housing 206. Similarly, any deflection force on second floating member 210 is not transferred an external portion of pump frame 200 and/or first housing 202.

FIG. 3 shows a pump 350 according to one embodiment of the present arrangements that includes pump frame 300 that is substantially similar to pump frame 100 of FIG. 1. Pump frame 300 includes a first housing 302, a first chamber 304, a second housing 306, a second chamber 308, a floating member 310 and a deflection-prevention feature 312, which are substantially similar to their counterparts in FIG. 1, i.e., first housing 102, first chamber 104, second housing 106, second chamber 108, floating member 110 and deflection-prevention feature 112. Coupled to pump frame 300 are a first cylinder 358 and a second cylinder 368, which have defined there a first cylinder chamber 360 and second cylinder chamber 370, respectively. During operation of pump 350, first cylinder chamber 360 is capable of receiving a first piston 356 and second cylinder chamber 370 is capable of receiving a second piston 366. A first manifold 372, coupled to first cylinder 358, control fluid to and from first cylinder chamber 360 and second manifold 374, coupled to second cylinder 368, control fluid to and from second cylinder chamber 370. First manifold 372 and second manifold 374 each receive fluid from a first inlet 276 and second inlet 378, respectively and that fluid is ultimately delivered to an outlet 380.

According to FIG. 3, a first motor 352, disposed and secured inside first housing 302, is configured to drive first piston 356. In certain preferred embodiments of the present arrangements, a first screw 354 (e.g., a ball screw or lead screw) is coupled to first piston 356 on one end and first motor 352 on the other end to drive first piston 356. First piston 356 is capable of protruding through a portion of pump frame 300 and occupies a space defined inside first cylinder chamber 360. During operation, first piston 356 may protrude into first cylinder chamber 360 by one or more predefined extents.

A second motor 362, disposed inside second housing 306 and secured inside floating member 310, is configured to drive a second piston 366. Preferably, a second screw 364, coupled to second motor 352 and second piston 366, is capable of driving second piston 366.

During an operative state of pump 350, in certain instances, first motor 352 causes a portion of first housing 302 to deform in an outward direction, i.e., away from first chamber 104. In other instances, second motor 362 causes floating member 310 to deform in an outward direction, i.e., away from second chamber 108. In both instances, however, deflection-prevention features 312 prevents a deflection-causing force experienced at a portion of first housing 302 from being transferred to second housing 306. Moreover, deflection-prevention feature 312 prevents deformation of floating member 310 from being transferred to first housing 302.

Second piston 366 is capable of protruding through another portion of pump frame 300 and occupies a space defined inside second cylinder chamber 370. During operation, second piston 366 may protrude into second cylinder chamber 370 by one or more predefined extents.

The present teachings recognize that any motor (e.g., alternating current motor or direct current motor) capable of driving a piston may be used in the present arrangements. In one embodiment of the present arrangements, first motor 352 and second motor 362 also includes a gearbox, which adjusts the rate of movement of a first screw 354 and/or second screw 364. However, the present teachings are not limited to a motor to drive first piston 356 and second piston 366. Other mechanisms may be used to drive first piston 356 and second piston 366 (e.g., pneumatic cylinder, actuator or belt drive coupled to an external motor).

During operation of pump 350 of FIG. 3, first motor 352 raises or lowers first screw 354, which in turn raises and lowers first piston 356 within the space inside first cylinder chamber 360. Similarly, second motor 362 adjusts the height of second screw 364 such that second piston 366 raises and lowers within second cylinder chamber 370. As first piston 356 moves up and down within first chamber cylinder 360, however, the volume within first cylinder chamber 360 is decreased or increased. Similarly, the available volume inside second cylinder chamber 370 is increased or decreased by the movement of second piston 366. Preferably, first cylinder chamber 360 and a second cylinder chamber 370 have the same internal volume.

First manifold 372 may control fluid to and from first cylinder chamber 360. Preferably, first manifold 372 is a three-way valve coupled to first cylinder chamber 360, first inlet 376, and outlet 380. In certain aspects of pump operation, first manifold 372 receives fluid from first inlet 376 (which may be part of first manifold 372) and transmits the fluid to first cylinder chamber 360. In other aspects of pump operation, first manifold 372 prevents fluid in first cylinder chamber 360 from entering and/or exiting while the fluid is pressurized. In another stage of pump operation, first manifold 372 allows pressurized fluid to travel from first cylinder chamber 360 to outlet 380.

Second manifold 374 may be coupled to second cylinder chamber 370, second inlet 378 and outlet 380. Similar to first manifold 372, second manifold 374 may receive a fluid, convey the fluid to second cylinder chamber 370, prevent the fluid within second cylinder chamber 370 from entering and/or exiting while the fluid is pressurized. In another function, second manifold 374 conveys the fluid from second cylinder chamber 370 to outlet 380.

FIG. 4 shows a pump 450 according to another embodiment of the present arrangements that includes pump frame 400 that is substantially similar to pump frame 200 of FIG. 2. Pump 450 includes a first housing 402, a first chamber 404, a second housing 406, a second chamber 408, a second floating member 410, a deflection-prevention feature 412, a first floating member 414, a first compartment 416, a second compartment 418 and a isolating component 420, which are substantially similar to their counterparts in FIG. 2, i.e., first housing 202, first chamber 204, second housing 206, second chamber 208, floating member 210 and deflection-prevention feature 212, first floating member 214, a first compartment 216, a second compartment 218 and a isolating component 220.

Pump 450 further includes substantially similar components as pump 350 of FIG. 3. By way of example, pump 450 includes a first motor 452, a first screw 454, a first piston 456, a first cylinder 458, a first cylinder chamber 460, a second motor 462, a second screw 464, a second piston 466, a second cylinder 468, a second cylinder chamber 470, a first manifold 472, a second manifold 474, a first inlet 476, a second inlet 478, and an outlet 480 which is substantially similar to their counterparts in FIG. 3, i.e., first motor 352, first screw 354, first piston 356, first cylinder 358, first cylinder chamber 360, second motor 362, second screw 364, second piston 366, second cylinder 368, second cylinder chamber 370, first manifold 372, second manifold 374, first inlet 376, second inlet 378, and outlet 380.

According to FIG. 4, first motor 452 and second motor 462 are secured to first floating member 414 and second floating member 410, respectively. During an operative state of pump 450, in certain instances, first motor 452 causes first floating member 414 to deform. In other instances, second motor 462 causes second floating member 414 to deform. Deflection-prevention feature 412 prevents the deflection force (which is capable of causing deformation) acting on second floating member 410 from being transferred to first housing 402. Similarly, deflection-prevention feature 412 prevents the deflection force acting on first floating member 414 from being transferred to second housing 406.

FIGS. 4 and 5 each show a pump 350 and 450 with two housings. However, the present teachings are not so limited. In other embodiments of the present arrangements, a pump may include multiple housings, each fitted with a corresponding ones of motor, piston, chamber cylinder and manifold. Working in conjunction with each other, the pistons may provide substantially continuous and substantially pulse-free fluid flow.

The current teachings also provide methods for dispensing a continuous fluid flow that do not use pumps 350 or 450 of FIGS. 3 and 4, respectively. In a preferred embodiment of the present teachings, pumps, such as those shown in FIGS. 3 and 4 are used. In a more preferred embodiments of the present teachings, the continuous fluid flow is also substantially pulse-free. During operation of pump 350, first piston 356 and second piston 366 work in concert (e.g., in a complementary fashion as described below) to generate a continuous fluid stream, preferably, at a predetermined fluid pressure and fluid rate.

In the complementary operation of the two pistons, first piston 356 and second piston 366 alternate between two strokes: an active stroke and a standby stroke. By way of example, during an active stroke, second piston 366 extends or delivers pre-pressurized fluid to outlet 380. Simultaneously (during the active stroke of second piston 366), first piston 356 engages in a standby stroke, at which stage first piston 356 receives fluid and pre-pressurizes the fluid. When second piston 366 completes the active stroke (e.g., second piston 366 extends to its furthest point within second cylinder chamber 370), first piston 356 and second piston 366 switch functions. In other words, in this stage, second piston is now in a standby stroke and first piston is in an active stroke. Continuing with this stage, first piston 356 now delivers its pre-pressurized fluid to outlet 380, while second piston 366 retracts, receives fluid and pre-pressurizes. First piston 456 and second piston 466 of pump 450, as described in FIG. 4, operate in substantially the same, but complementary manner, to generate a continuous, and preferably pulse-free, fluid flow.

In one embodiment of the present teachings, FIG. 5 provides a method 500 of dispensing a continuous fluid flow. For ease of illustration, pump 350 of FIG. 3 is used to describe the method of dispensing a continuous fluid flow, however, pump 450, of FIG. 4, may be used in a substantially similar manner. Method 500 begins with a step 502, which includes filling a first cylinder chamber 360, having a first predefined volume, with fluid received from first fluid inlet. By way of example and with reference to FIG. 3, a first cylinder chamber 360, having a first predefined volume, is filled with fluid received from first fluid inlet 376. This step is also referred to as the standby stroke inside the first cylinder chamber 360. During this step, first manifold 372 is configured to receive and convey fluid from inlet 376 to first cylinder chamber 360. Simultaneously, first piston 356 retracts within first cylinder chamber 360. Motor 352 engages screw 354, which retracts first piston 356 to a predetermined lower position that, in certain instances, is used to define the fluid volume that will be transmitted during the active stroke of first piston 356. During the filling step of 502, first manifold 372 is configured so as to prevent any entry or exit of fluid from first cylinder chamber 360.

First piston 356 may be extended or retracted within first cylinder chamber 360 to adjust the fluid volume that will be transmitted during the active stroke. First piston 356 may be retracted to increase the fluid volume within first cylinder chamber 360. Conversely, first piston 356 may be extended into first cylinder chamber 360 to reduce the fluid volume within first cylinder chamber 360. In this manner, a single pump 350 may be used to operate at different continuous fluid flow rates. In certain embodiment of the present arrangements, fluid flow to fluid outlet 380 has a flow rate that ranges from about 0.00001 ml/min to about 1000 ml/min. In addition, the present arrangements provide for the fluid flow to be adjusted during operation of pump 350 by adjusting the fluid volume within the cylinder chambers.

In preferred embodiments of the present teachings, step 502 involves pressurizing the fluid in first cylinder chamber 360 to a predetermined or predefined pressure value, P1. Reducing the volume within first cylinder chamber 360 pressurizes the fluid in first cylinder chamber 360. This can be accomplished by increasing the space occupied by first piston 356 inside second cylinder chamber 360, which decreases the volume available inside first cylinder chamber 360 and increases the fluid pressure. The fluid volume and pressure may be manipulated in a similar manner within second cylinder chamber 370 using second piston 366.

Pressurizing the fluid is performed by extending first piston 356, using first motor 352, from the predetermined lower position to a second position to reduce the volume in first chamber 110 and correspondingly increases the fluid pressure. Preferably, the second position corresponds to the predetermined fluid pressure, P1. In one embodiment of the preferred teachings, the second position is calculated by determining the amount of volume that is to be reduced to achieve the predetermined pressure of the fluid. A second predetermined pressure value, P2, in second cylinder chamber 370 may be determined in the same manner. In one preferred embodiment of the present teachings the first predefined pressure value and the second predetermined pressure value are substantially the same (i.e., P1=P2). In another preferred embodiment of the present arrangements, the first predefined pressure value and the second predefined pressure value is a high pressure. In another embodiment of the present teachings, the first predefined pressure value and the second predefined pressure value ranges from about 500 psi to about 50,000 psi.

Next, a step 504 is carried out. Step 504 includes dispensing the predefined amount of fluid present inside the first cylinder chamber to a fluid outlet. By way of example, in FIG. 3, the predefined amount of fluid present inside first cylinder chamber 360 is dispensed through first manifold 372 to fluid outlet 380. This step is also referred to as the active stroke. First motor 352 extends first piston 356 and pushes the preferably pre-pressurized fluid from first cylinder chamber 360 through first manifold 372 to outlet 380, while preventing any additional fluid from entering through first inlet 376.

A step 506, which is preferably carried out contemporaneously with step 504, includes filling a second chamber, having a second predefined volume, with fluid received from a second fluid inlet. By way of example and with reference to FIG. 3, filling second cylinder chamber 370 that has a second predefined volume. The fluid is received through second manifold 374 from second fluid inlet 378. In certain preferred embodiment of the present teachings, the first predefined volume of first cylinder chamber 360 is substantially similar to the second predefined volume of second cylinder chamber 360. In other embodiments of the present teachings, the first predefined volume of first cylinder chamber 360 is different from the second predefined volume of second cylinder chamber 360. In certain embodiment of the present teachings, each of the first predefined volume and the second predefined volume is a value that ranges from about 1 ml and about 1000 ml.

Another step 508 includes exerting, during the dispensing step 504, a deflection-causing force on a first housing that is disposed adjacent to the first cylinder chamber. In FIG. 3, by way of example, first housing 302 is shown adjacent to first cylinder chamber 360 and a deflection-causing force is received at first housing 302 when the fluid inside first cylinder chamber is dispensed. During an active stroke (i.e., step 504)—when first piston 356 is forcing pressurized fluid from first cylinder chamber 360—motor 352 applies a large downward force, F1, to a portion of first housing 302 on which motor 352 is attached. The force, F1, applied to first housing 302 is equal and opposite to upward force of piston 356 and causes first housing 302 to flex in an outward direction or away from first chamber 304. Similarly, an equal and opposite force, F2, is applied to an opposing portion of pump frame 300 causing it to flex in an outward direction or away from first chamber 304. The terms “opposing portion of pump frame 350,” as used herein, refers to the portion of pump frame 350 that is adjacent to first and/or second cylinders 358 and 368 of FIG. 3.

Next, a step 510 includes preventing, using a deflection-prevention feature, transfer of the deflection-causing force from the first housing to the second housing, which is disposed adjacent to the second cylinder chamber and is disposed adjacent to the first housing. By way of example and with reference to FIG. 3, a deflection-prevention feature 312 prevents transfer of the deflection-causing force from first housing 302 to a second housing 306, which is disposed adjacent to second cylinder chamber 370 and first housing 302. The force, F1, applied to the portion of first housing 302 causes first housing 302 to deflect in a downward direction. In the example of FIG. 3, deflection-prevention features 312 prevents a corresponding deflection of floating member 310 of second housing 306, because floating member 310 is isolated from the deflection-causing force acting upon first housing 302. Thus, second motor 362 and second piston 366 do not deflect.

An equal and opposite force, F2, is also applied to the opposing portion of pump frame 350 causing it to deflect upward and/or outward. This upward and/or outward deflection of the opposing portions of pump frame 350 causes first cylinder 358, second cylinder 368, and second housing 306 to deflect upward and/or outward. In the presence of deflection-prevention feature, however, floating member 310 is isolated from first housing 302, and therefore, floating member 310 is free to deflect by the same distance and in the same direction as the opposing portion of pump 350. Similarly, second motor 362, second piston 366 and second cylinder chamber 370 deflects by the same distance and in the same direction as the opposing portion of pump frame 350. As a result, the volume of second cylinder chamber 370 remains the same and/or is unaffected.

While second piston 366 performs the standby stroke according to the present teachings, the volume within second cylinder chamber cylinder 370 remains constant. As a result, during pre-pressurization, the fluid is pre-pressurized to second predetermined pressure, P2, and is not affected by the activity of or the forces exerted by first piston 356. Thus, a pulse-free fluid flow is established through outlet 380. Preferably, the flow rate does not vary more than 0.1% from an average fluid flow rate.

In the absence of a deflection-prevention feature, a first housing is coupled to a second housing. As a result, any deflection-causing force acting upon either first housing or second housing is transferred to the other housing which results in a fluid flow output with pressure and/or fluid rate pulsations. By way of example, during a first piston's active stroke, the first piston pushes pressurized fluid from a first cylinder chamber to an outlet. As explained above, the first piston generates a deflection-causing force on a portion of the first housing on which a first motor is attached and a second force on an opposing portion of the first housing. While the first piston is in active stroke, the second piston undergoes a standby stroke. Due to the coupled nature of first housing and second housing in the absence of a deflection-prevention feature, the deflecting force also deflects second motor and thus second piston within second cylinder chamber. The deflective force lowers the second motor, which simultaneously lowers the position of second piston within second cylinder chamber. In addition, the second force on an opposing portion of the first housing generated by first piston pushes the second cylinder chamber in an outward direction and away from the second piston. As a result, in the presence of deflection-causing forces, the fluid volume in a second cylinder chamber is greater than the second predefined fluid volume, which remained fixed in the presence of deflection-prevention feature.

In the absence of deflection-prevention feature, in a pump frame or a pump, fluid flow is dispensed in a pulsed manner. At the end of the first piston's active stroke, a first manifold closes fluid flow to the fluid output and opens to receive fluid from a first inlet. At this stage, the fluid inside the first cylinder chamber is under the same low pressure as the fluid being introduced into the first cylinder chamber by a first manifold. The deflection-causing force, F1, generated by a first piston during the active stroke, is no longer exerted on a portion of the first housing, to which a first motor is attached. Consequently, a second force, F2, is no longer exerted on an opposing portion of the pump frame. The pressure relief causes the first and the second housings to return to a non-deflected state. Further, the second piston is forced further into the second cylinder chamber and the second cylinder returns to its original, lower position in this non-deflected state. As a result, the volume in second cylinder chamber is rapidly reduced. The reduced volume in the second cylinder chamber leads to either to a greater fluid flow rate at an output or the pressure in the second cylinder chamber spikes momentarily causing the flow to be pulsed. In the next stage, when the second piston is at the end of its active stroke, the fluid flow rate may spike or the pressure in the first cylinder chamber may momentarily spike.

Step 510 also applies when pump 450 of FIG. 4, instead of pump 350 of FIG. 3, is used. Referring back to pump 450 deflection-prevention feature 412 prevents transfer of a deflection-causing force from the first housing 402 to a second housing 406. In an active stroke, first piston 456 applies a force to push the pressurized fluid out of first cylinder chamber 460. In turn, first motor 452 applies a large downward force, F1, against first floating member 414 on which motor 452 is attached. The force, F1, applied to first floating member 414 causes first floating member 414 to deflect in a downward direction. Deflection-prevention feature, however, prevents first floating member 414's deflection from contacting second floating member 410 or any other portion of pump frame 400. As a result, the deflection of first floating member 414 does not cause a deflection of second floating member 410 of second housing 406 because they are isolated from each other. As a result, second motor 462 and second piston 466 do not deflect due to deflection-causing force acting at first floating member 414.

In one embodiment of the present arrangements, method 500 includes one or more additional steps. Once such step includes dispensing the predefined amount of fluid inside second cylinder chamber through second manifold to the fluid outlet. By way of example and with reference to FIG. 3, the predefined amount of fluid inside second cylinder chamber 370 is dispensed through second manifold 374 to fluid outlet 380. This step is substantially similar to step 504, except that fluid is dispensed from second cylinder chamber 370 rather than first cylinder chamber 360.

Another such step, which is substantially similar to step 502, includes filling first cylinder chamber 360 with fluid received through first manifold from first fluid inlet. In FIG. 3, by way of example, the first cylinder chamber 360 is filled with fluid received through first manifold 372 from first fluid inlet 376. This step is carried out contemporaneously with the above-mentioned dispensing step associated with second cylinder chamber 370.

A yet another such step includes exerting, during dispensing from the second cylinder chamber, a deflection-causing force on the second housing. By way of example, as second piston 366 of FIG. 3 pushes fluid from second cylinder chamber 370, a deflection-causing force pushes floating member 310 of second housing 3012 in an outward direction.

Yet another step includes preventing, using deflection-prevention feature 312, transfer of the deflection-causing force from second housing 306 to first housing 302. By way of example and with reference to FIG. 3, deflection-prevention feature 312 prevents transfer of the deflection-causing force from second housing 306 to first housing 302. Deflection-prevention feature 312 provides a cavity into which floating member 310 may extend without contacting pump frame or first housing 302. The deflection-cause force of second housing 306 is not transferred to first housing 302.

The above-described steps allow pumps 350 and 450 to provide substantially continuous and substantially pulse-free fluid flow using a single pump frame. The present arrangements allow for a compact pump designs that may be critical is certain industrial applications that require a compact, high-pressure pump with pulsation-free fluid flow. By way of example, pumps 350 and 450 may be used where laboratory settings that measure micro-flow rates, which are sensitive to any pulse caused by the pump.

Although illustrative embodiments of this invention have been shown and described, other modifications, changes, and substitutions are intended. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure, as set forth in the following claims. 

What is claimed is:
 1. A pump comprising: a pump frame comprising: two or more housings disposed inside pump frame; one or more deflection-prevention features that, during an operative state of said pump, prevents transfer of a deflection force received at one of said housings to another of said housings; and two or more motors, each disposed inside one of said housings and configured to drive a corresponding piston; two or more cylinders, each disposed adjacent to a corresponding one of said housings and each of said cylinder having defined therein a cylinder chamber and wherein one end of one of said corresponding pistons capable of protruding into a corresponding one of said cylinder chambers by a corresponding predefined extent; two or more manifolds, each includes or is communicatively coupled to a fluid inlet, and wherein each of said manifold introduces an amount of fluid received from one of said fluid inlets into said corresponding one of said cylinder chambers; a fluid outlet for dispensing fluid in a substantially pulse-free manner; and wherein said deflection-prevention feature prevents deformation of one of said housings and/or another of said housings by preventing, during an operative state of said pump over a period of time, transfer of said deflection force received at one of said housings to another of said housings, and thereby allowing each of said corresponding pistons to protrude into said corresponding cylinder chamber by said corresponding predefined extent such that said fluid outlet dispenses said fluid in a substantially pulse-free manner.
 2. The pump of claim 1, wherein one or more of said deflection-prevention features are communicatively coupled to one of said chambers and is not communicatively coupled to another of said chambers, and one or more of said deflection-prevention features at least partially surrounds one of said housings to prevent coupling of one of said housings with another of said housings or to effectively isolate, at or near a location of said deflection-prevention feature, one of said housings from another of said housings.
 3. The pump of claim 1, wherein one or more of said deflection-prevention features comprises a structural boundary having defined therein a cavity that is filled with air and/or material.
 4. The pump of claim 1, wherein said two or more housings include: (i) a first housing having defined therein a first chamber; (ii) a second housing having defined therein a second chamber; wherein said two or more motors include: (i) a first motor disposed inside said first housing and configured to drive a first piston; (ii) a second motor disposed inside said second housing and configured to drive a second piston; wherein said two or more cylinders include: (i) a first cylinder disposed adjacent to said first housing and said first cylinder having defined therein a first cylinder chamber and wherein one end of said first piston is capable of protruding into said first cylinder chamber by a first predefined extent; (ii) a second cylinder disposed adjacent to said second housing and said second cylinder having defined therein a second cylinder chamber and wherein one end of said second piston is capable of protruding into said second cylinder chamber by a second predefined extent; wherein said two or more manifold include: (i) a first manifold includes or is communicatively coupled to a first fluid inlet, and wherein said first manifold introduces a first amount of fluid received from said first fluid inlet into said first cylinder chamber; (ii) a second manifold includes or is communicatively coupled to a second fluid inlet, and wherein said second manifold introduces a second amount of fluid received from said second fluid inlet into said second cylinder chamber; and wherein said deflection-prevention feature allows said first piston to continue to protrude into said first cylinder chamber by said first predefined extent and allows said second piston to continue to protrude into said second cylinder chamber by said second predefined extent.
 5. The pump of claim 2, wherein said first cylinder chamber is designed to store a first predefined volume of said fluid and said second cylinder chamber is designed to store a second predefined volume of said fluid, and wherein said deflection-prevention feature prevents change in amounts of said first predefined volume of fluid stored inside said first cylinder chamber and/or prevents change in amounts of second predefined volume of fluid inside said second cylinder chamber.
 6. The pump of claim 5, wherein each of said first predefined volume and said second predefined volume is a value that ranges from about 1 ml and about 1,000 ml.
 7. The pump of claim 1, further comprising two or more screws, each of which is coupled to said corresponding piston and said corresponding motor such that, during an operative state of said pump, each of said corresponding motor drives said corresponding screw.
 8. The pump of claim 1, wherein when said fluid outlet dispenses said fluid in a substantially pulse-free manner, said flow rate does not vary more than 0.1% from an average fluid flow rate.
 9. The pump of claim 1, wherein during operation of said pump, at least two of said pistons operate in a complementary manner, and thereby allowing said pump to continuously dispense said fluid from said fluid outlet.
 10. The pump of claim 1, wherein said deflection-prevention feature includes two or more compartments, each of which is isolated from the other, and one of said housings being disposed inside one of said compartments and another of said housings being disposed inside another of said compartments and in an assembled configuration of said pump, said deflection-prevention feature at least partially surrounds at least two of said housings to prevent coupling of and/or contact between said at least two of said housings.
 11. The pump of claim 1, wherein said pump is a dual-piston reciprocating pump or metering pump.
 12. The pump of claim 1, wherein at least one of said housings includes a floating member that is: (i) part of one of said housings; (ii) designed to receive said deflection force from one of said motors and/or said pistons; and (iii) isolated from said another of said housings.
 13. A pump frame comprising: a first housing having defined therein a first chamber; a second housing including a floating member and said second housing having defined therein a second chamber, and said second housing is disposed adjacent to said first housing inside said pump frame; and a deflection-prevention feature communicatively coupled to said first chamber, and not communicatively coupled to said second chamber, and said deflection-prevention feature at least partially surrounds said floating member to prevent coupling, at or near a location of said deflection-prevention feature, of said second housing with said first housing or to effectively isolate, at or near a location of said deflection-prevention feature, said second housing from said first housing.
 14. The pump frame of claim 14, wherein said floating member defines a partial boundary of said second chamber and during operation of said pump, said floating member receives a deflection-causing force.
 15. The pump frame of claim 14, wherein said deflection-prevention feature surrounds at least one corner of said second housing that is proximate a corner of said first housing.
 16. The pump frame of claim 14, wherein a distance between said first housing and a boundary defining said floating member that is closest to said first housing is a value that exceeds about 0.5 mm.
 17. A pump frame comprising: a first housing having defined therein a first chamber; a second housing having defined therein a second chamber, and said second housing is disposed adjacent to said first housing inside said pump frame; and deflection-prevention feature includes two or more compartments, each of which is isolated from the other by an isolating component, and said first housing is disposed inside one of said compartments and said second housing is disposed inside another of said compartments and in an assembled configuration of said pump, said deflection-prevention feature at least partially surrounds said first housing and said second housing to prevent coupling of said first housing with said second housing.
 18. The pump of claim 18, wherein said isolating component includes a structural boundary having defined therein a cavity that is filled with air and/or material.
 19. A method of dispensing a continuous fluid flow, said method comprising: filling a first cylinder chamber, having a first predefined volume, with said fluid received through a first manifold from a first fluid inlet; dispensing said first predefined amount of said fluid present inside said first cylinder chamber through said first manifold to a fluid outlet; filling a second cylinder chamber, having a second predefined volume, with said fluid received through a second manifold from a second fluid inlet, and wherein said filling is carried out contemporaneously with said dispensing; exerting, during said dispensing, a deflection-causing force on a first housing that is disposed adjacent to said first cylinder chamber; and preventing, using said deflection-prevention feature, transfer of said deflection-causing force from said first housing to a second housing, which is disposed adjacent to said second cylinder chamber and is disposed adjacent to said first housing.
 20. The method of claim 20, further comprising pressurizing said fluid inside said first cylinder chamber to a first predefined pressure value, and wherein said pressurizing is carried out prior to said dispensing from said first cylinder chamber.
 21. The method of claim 20, further comprising: dispensing said predefined amount of said fluid inside said second cylinder chamber through said second manifold to said fluid outlet; filling a first cylinder chamber having said predefined volume with said fluid received through a first manifold from said first fluid inlet, and wherein said filling is carried out contemporaneously with said dispensing; exerting, during said dispensing from said second cylinder chamber, a deflection-causing force on said second housing; preventing, using said deflection-prevention feature, transfer of said deflection-causing force from said second housing to a first housing.
 22. The method of claim 22, further comprising pressurizing said fluid inside said second cylinder to a second predefined pressure value.
 23. The method of claim 23, wherein said first predefined pressure value and said second predefined pressure value is a high pressure that ranges from about 500 psi to about 50,000 psi.
 24. The method of claim 23, wherein said fluid flow to said fluid outlet has a flow rate that ranges from about 0.00001 ml/min to about 1000 ml/min. 